Wireless communications systems using multiple radios

ABSTRACT

The present invention relates to a communication system and methods of use thereof. The system includes sets of complementary radios for transmitting and receiving signals to achieve high reliability and reduced costs. The sets of complementary radios are in wireless communication with each other. A new connection is made by selecting from amongst the complementary radios. Switching between complementary radios during a connection is also permitted. Optimized protocols and hardware for implementing the system are disclosed.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.61/026,710, filed Feb. 6, 2008; U.S. Provisional Application No.61/114,449, filed Nov. 13, 2008; U.S. Provisional Application No.61/114,427, filed Nov. 13, 2008; U.S. Provisional Application No.61/114,431, filed Nov. 13, 2008; and U.S. Provisional Application No.61/114,418, filed Nov. 13, 2008, which applications are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates generally to wireless communicationsystems and specifically to wireless communications systems usingmultiple radios.

BACKGROUND OF THE INVENTION

Wireless communications are implemented by any of a variety of radiotechnologies, depending on the type of application. Cellular phones, forexample, may use the Global System for Mobile communications (GSM™), theIS-54 Time Division Multiple Access (TDMA) or the IS-95 Code DivisionMultiple Access (CDMA) radio technologies, whereas a wireless local areanetwork may use Wi-Fi™, Bluetooth™ or ZigBee® radio technologies. In anad-hoc, or peer-to-peer, network, a wireless device communicatesdirectly with another wireless device. In an infrastructure network, awireless device communicates with another wireless device through one ormore intermediary gate devices, such as a base station or an accesspoint. Generally, a wireless device uses a single radio technology toeffect communication with its peer (in the case of a peer-to-peernetwork) or with the access point (in the case of an infrastructurenetwork). In the prior art, dual radios are used in a wireless device tosupport different air interface standards, in order to providecompatibility with different wireless service providers. For example, adual-radio device may support GSM, a cellular phone service, and Wi-Fi,a wireless Local Area Network (LAN) service, and uses one of these tworadios for communication, depending on which service (GSM or Wi-Fi) isavailable in a geographic area. Generally, such a wireless deviceselects and uses a single radio for the duration of the connection orservice.

The present invention relates to an innovative wireless communicationssystem employing multiple radios. The communications system selectsamongst and switches between multiple radios—possibly multipletimes—while a connection or session is in progress. This switchingallows the communications system to achieve one or more of the followingperformance objectives:

-   -   Maximize communications reliability and robustness against        interference and other impairments    -   Minimize interference to co-existing users    -   Minimize power consumption    -   Accommodate any disparity between the uplink and downlink        bandwidths

Moreover, the multiple radio system can reduce the physical footprint ofthe radio nodes and lead to improved data rates and communication range.

When a single radio type is used, the degrees of freedom are limited fordesired optimization. A given radio can be optimized, for example, bythe following means:

-   -   Switch transmission channels within the given band to        dynamically mitigate interference (to improve reliability).    -   Adjust transmitted power as needed (to improve power dissipation        or reliability).

There are few other meaningful operations that can be performed tooptimize single-radio systems. With a single type of radio, it isparticularly challenging to design a system that calls for simultaneousoptimization of multiple factors—for example, optimization of all ofthese four factors: link range/reliability, node power, node cost andlow interference to other radios. If a radio is optimized for onefactor, it will typically negatively impact other factors. For example,if power is reduced for a low-power design, it would typically reducethe range/reliability. If an ultra-wideband (UWB) radio is deployed tocause minimum interference to other radios, it would result in shortrange, high complexity and potentially high cost (the UWB receiver beingcomplex and high power).

Accordingly, a radio scheme is desired for a wireless communicationsystem that addresses the optimization of multiple factors.

SUMMARY OF THE INVENTION

In one aspect, the present invention discloses a node comprising a firstradio constructed and arranged to function as at least one of atransmitter and a receiver, and a second radio constructed and arrangedto function as at least one of a transmitter and a receiver, wherein thefirst radio and second radios are complementary. In some embodiments,the first radio is constructed and arranged to transmit and to receivesignals and the second radio is also constructed and arranged totransmit and to receive signals.

In another aspect, the present invention discloses a communicationsystem comprising a node as described above, the node forming a firstnode and the first and second radios forming a first set ofcomplementary radio. The communication further comprises a second node,the second node including a second set of complementary radios fortransmitting and receiving signals. The first and second nodes are inwireless communication via the first and second sets of complementaryradios.

In another aspect, the present invention discloses a communicationsystem comprising a node as described above, the node forming a firstnode and the first and second radios forming a first set ofcomplementary radios. The communication further comprises a second nodecomprising a second set of complementary radios for transmitting andreceiving signals. The first and second nodes are constructed andarranged to wirelessly communicate via both the first and second sets ofcomplementary radios.

In another aspect, the present invention discloses a communicationsystem comprising a base node for transmitting and receiving signals,the base node comprising a first plurality of resources; and at leastone peripheral node for transmitting and receiving signals, the at leastone peripheral node comprising a second plurality of resources. The basenode and the at least one peripheral node are in wireless communicationand the first plurality of resources is greater than the secondplurality of resources.

In another aspect, the present invention discloses a communicationsystem comprising a base node comprising a first set complementaryradios for transmitting and receiving signals, and at least oneperipheral node comprising a second set of complementary radios fortransmitting and receiving signals. The base node and the at least oneperipheral node are constructed and arranged to wirelessly communicatevia both the first and second sets of complementary radios. In someembodiments, the base node consumes more power than each individualperipheral node.

In another aspect, the present invention discloses a communicationsystem comprising a base node comprising a first set of complementarymeans for transmitting and receiving signals, and at least oneperipheral node comprising a second set of complementary means fortransmitting and receiving signals. The base node and the at least oneperipheral node comprise a means for wirelessly communicating via boththe first and second sets of complementary means for transmitting andreceiving signals. In some embodiments, the base node consumes morepower than each individual peripheral node.

In another aspect, the present invention discloses a method for usingtwo or more complementary radios in a communication system comprisingeither or both of the following steps: 1) selecting one or more of thecomplementary radios to form a connection; and 2) switching between oneor more of the complementary radios to maintain a connection.

In another aspect, the present invention discloses a method for usingtwo or more complementary radios in a communication system comprisingeither or both of the following steps: 1) activating at least onecomplementary radio to form a connection; and 2) activating one or moreinactive complementary radios to maintain a connection.

In another aspect, the present invention discloses a method for usingtwo or more complementary radios in a communication system comprisingeither or both of the following steps: 1) selecting one complementaryradio from the at least two complementary radios to form a newconnection; and 2) switching between a first complementary radio and asecond complementary radio during a connection.

In some embodiments of the above methods, only one of the complementaryradios is selected or activated to form a connection and only one of thecomplementary radios is switched to or activated to maintain aconnection. In other embodiments of the above methods, the communicationsystem selects which of the complementary radios is active. In otherembodiments of the above methods, the communication system selects whichof the complementary radios is used to form or maintain a connection inorder to meet a performance objective. In other embodiments of the abovemethods, the transmitter associated with each of the complementaryradios transmits substantially simultaneously and the receiverassociated with each of the complementary radios combines signals fromthe complementary radios.

In another aspect, the present invention discloses a device forimplementing a complementary radio system comprising two or morecomplementary radios, means for selecting one or more of thecomplementary radios to form a connection, and means for switchingbetween one or more of the complementary radios during the connection.

In another aspect, the present invention discloses a device forimplementing a complementary radio system comprising two or morecomplementary radios, means for activating one or more of thecomplementary radios simultaneously, means for transmitting a signalfrom each of the complementary radios substantially simultaneously, andmeans for combining signals from the complementary radios.

In another aspect, the present invention discloses a method forswitching radio connections in a complementary radio communicationsystem, comprising establishing a forward radio connection and a reverseradio connection between a first node and a second node, each nodecomprising two or more complementary radios, wherein the forward radioconnection transmits data from the first node to the second node, andthe reverse radio connection transmits data from the second node to thefirst node. The method further comprises monitoring the communicationquality of the forward radio connection on the second node until thecommunication quality of the forward radio connection falls below aperformance criteria, then transmitting a control message from thesecond node to the first node using the reverse radio connectionestablished above. The control message comprises a message to switch toan alternate radio connection selected by the second node. Theconnection is then reestablished using the alternate radio connection.In some embodiments of the method, transmission of the control messageis repeated until the first node transmits data to the second node onthe alternate radio connection within a predetermined time interval. Insome embodiments, the second node continues to listen on the forwardradio connection in the initial step until the first node transmits datato the second node on the alternate radio connection within thepredetermined time interval. In some embodiments, the data transmittedfrom the first node to the second node comprises an acknowledgement inresponse to the control message. In some embodiments, the second nodeconsumes more resources than the first node.

In another aspect, the present invention discloses a receiver comprisinga means for amplification, a configurable means for filtering comprisinga means for communication with the amplification means, and at least oneconfigurable device comprising means for communication with theconfigurable filter. The receiver also comprises at least one means foranalog to digital conversion further comprising means for communicationwith the at least one configurable device. The configurable means forfiltering is constructed and arranged to function as a bandpass filterwhen the receiver is used as a narrowband receiver and to function as alow pass filter when the receiver is used as an ultra-wideband receiver.

In another aspect, the present invention discloses a receiver comprisinga means for amplification, a configurable means for filtering inelectronic communication with the means for amplification, and at leastone configurable device electrically communicable with the configurablemeans for filtering. The receiver also comprises at least one means foranalog to digital conversion in electrical communication with the atleast one configurable device. The configurable means for filtering isconstructed and arranged to function as a bandpass filter when thereceiver is used as a narrowband receiver and to function as a low passfilter when the receiver is used as an ultra-wideband receiver.

In another aspect, the present invention discloses a receiver comprisingan amplifier, a configurable filter comprising means for communicationwith the amplifier, at least one configurable device comprising meansfor communication with the configurable filter, and at least one analogto digital converter comprising means for communication with the atleast one configurable device. The wherein the configurable filter isconstructed and arranged to function as a bandpass filter when thereceiver is used as a narrowband receiver and to function as a low passfilter when the receiver is used as an ultra-wideband receiver.

In another aspect, the present invention discloses a receiver comprisingan amplifier, a configurable filter in electronic communication with theamplifier, at least one configurable device in electrical communicationwith the configurable filter, and at least one analog to digitalconverter in electrical communication with the at least one configurabledevice. The configurable filter is constructed and arranged to functionas a bandpass filter when the receiver is used as a narrowband receiverand to function as a low pass filter when the receiver is used as anultra-wideband receiver.

In another aspect, the present invention discloses a receiver comprisingan amplifier, a configurable filter coupled to the amplifier, a bank ofconfigurable devices coupled to the configurable filter, and a pluralityof analog to digital converters coupled to the bank of configurabledevices. The configurable filter is configured into a bandpass filterwhen the receiver is utilized as a narrowband receiver and is configuredinto a low pass filter when the receiver is utilized as anultra-wideband receiver.

In some embodiments of the receivers of the invention, the configurabledevice is configured as a means for mixing when the receiver is used asa narrowband receiver and is configured as a means for switching whenthe receiver is an ultra-wideband receiver.

In other aspects, the present invention discloses a kit comprising oneor more nodes as described above. In still other aspects, the presentinvention discloses a kit comprising a communication system as describedabove. In other aspects, the present invention discloses a kitcomprising one or more receivers as described above.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 illustrates a wireless communications system deploying a singleradio type;

FIG. 2 illustrates a conventional asymmetric wireless communicationsystem deploying a single radio type;

FIG. 3 illustrates a system for deploying multiple radios in accordancewith the present invention;

FIG. 4 illustrates the different elements of a digital radio;

FIG. 5 illustrates one embodiment of the multi-radio scheme containingone narrow band (NB) radio and one ultra-wideband (UWB) radio;

FIG. 6 illustrates the range of the UWB/NB radio system in accordancewith an embodiment;

FIG. 7 illustrates a multi-radio system in accordance with anembodiment. Multiple antennas can be used for the Wi-Fi radio of theA-Node to increase robustness;

FIG. 8 illustrates a flow chart for addressing the constrainedoptimization approach;

FIG. 9 illustrates an approach for reliably switching radio connectionson a base node;

FIG. 10 illustrates an approach for reliably switching radio connectionson a peripheral node in communication with the base node of FIG. 9;

FIG. 11 illustrates a modification to FIG. 9 for reliably switchingradio connections on a base node;

FIG. 12 illustrates an alternate approach for reliably switching radioconnections on a base node;

FIG. 13 illustrates an approach for reliably switching radio connectionson a peripheral node in communication with the base node of FIG. 12;

FIG. 14 illustrates a modification to FIG. 12 for reliably switchingradio connections on a base node;

FIG. 15 illustrates a generic narrowband receiver;

FIG. 16 illustrates the receiver configured into an ultra-wide band(UWB) receiver;

FIG. 17 illustrates a generic transmitter configured as a narrowbandtransmitter in accordance with the present invention;

FIG. 18 shows that, when the transmitter is in UWB mode, a single pulseto a switch is provided such that a single transmitter can be easilyreconfigured into either a narrowband or a UWB mode;

FIG. 19 illustrates an embodiment of a circuit which can provide eithernarrowband or UWB mode dependent upon the input signal to thetransistor;

FIG. 20 illustrates the reconfigurable receiver implemented in CMOStechnology;

FIG. 21 shows the layout of the inductors in the present invention; and

FIGS. 22A and 22B show the operation of the reconfigurable transmitterin more detail.

DETAILED DESCRIPTION OF THE INVENTION

A wireless communications system 10 comprises at least two nodes 12 and14 communicating with each other as shown in FIG. 1. The two nodes 12and 14 communicate through a radio system, 16 a and 16 b, respectively,via antennas 20 a and 20 b. The radios on both sides (16 a and 16 b) areof the same type, called Radio X. As shown, the data can be optionallypreprocessed by processor 18 a, making it suitable for radiotransmission, before it is fed to radio system 16. On the receiving end,the data can be post processed by the processor 18 b to recover theoriginally sent data. Based on the requirements of a given system, theradio system 16 can be optimized in certain ways. Following are someexamples of the factors that can be optimized:

-   -   Low power dissipation of nodes;    -   Low cost of nodes;    -   High link reliability (immunity to fading, interference and        noise);    -   Small physical foot print of the nodes;    -   High data rates;    -   Large communication range; or    -   Cause minimum interference to other radio systems (e.g., quiet        radio).

There can be many more optimization factors. As shown in FIG. 1,conventional communication systems employ a single radio type X that canbe designed to achieve certain level of optimization. Some examples ofRadio X are Wi-Fi, Bluetooth™ and Zigbee®.

I. Asymmetric Wireless Systems

In many applications there exists an asymmetry between two nodeswirelessly communicating with each other, as shown in FIG. 2. In thesesystems, there is an anchor node (A-Node) 102 which collects data fromone or more nodes called peripheral nodes (P-Node or P-Nodes) 104 a-104n. The P-Nodes 104 a-104 n typically operate using a small power source(e.g., a small battery or an energy harvesting device). The A-Node 102typically has access to a higher capacity power source (larger batteryor a power supply). Furthermore, in such systems, P-Nodes 104 a-104 nprimarily transmit the data to A-Node 102. The data flow from A-Node 102to P-Nodes 104 a-104 n is usually minimal, comprising mostly signals tocontrol the P-Nodes Nodes 104 a-104 n. In summary, there can be anasymmetry in terms of data flow and power sources in the system of FIG.2. The following are some examples of this type of asymmetric systems.

Wireless healthcare systems: In wireless health monitoring systems,P-Nodes 104 a-104 n can reside on wireless patches attached to aperson's body or they can reside on wireless devices implanted within aperson's body. These wireless patches/devices collect physiological datafrom various body sensors attached to P-Nodes 104 a-104 n and wirelesslytransmit data to the A-Node 102 within the range of P-Nodes 104 a-104 n.The P-Nodes 104 a-104 n can send the data to the A-Node 102 usingvarious schemes, e.g., continuously, periodically or episodically. Someexamples of physiological data sent by P-Nodes 104 a-104 n areelectrocardiogram (ECG), electroencephelogram (EEG), electromyogram(EMG), heart rate, temperature, saturation of peripheral oxygen (SpO2),respiration, blood pressure, blood glucose and patient's physicalactivity (movement). The A-Node 102 receiving data from P-Nodes 104a-104 n, will normally reside in some type of patient monitoring devicethat collects, analyzes and manages the physiological data. Someexamples of patient monitors are bed-side patient monitors in hospitals,Holter monitors (ambulatory electrocardiography device) for ambulatoryECG, blood glucose monitors, wearable physiological parameter monitorsfor athletes, safety monitoring units for industrial workers andSmartPhones supporting patient monitoring.

Wireless industrial sensors: In such systems, P-Nodes 104 a-104 n canreside on various industrial or home devices such as furnaces, smokedetectors, movement detectors, electrical/gas/water usage meters, etc.The P-Nodes 104 a-104 n can transmit various types of sensor data (e.g.temperature, mechanical stress, chemicals, and meter readings) or someother type of information. The A-Nodes 102 can reside on portablereaders, data gathering computers, wireless access points, etc.; thesedevices wirelessly receive data from the devices connected to P-Nodes104 a-104 n.

Active Radio-frequency identification (RFID): In such applications,P-Nodes 104 a-104 n can reside on various assets that need to be trackedor inventoried, such as capital equipment in hospitals, factories,offices, etc. The A-Nodes 102 can reside on devices such as portablereaders, wireless access points and computers. These devices willwirelessly receive data from the devices having P-Nodes 104 a-104 n.Furthermore, locations of asset items can be tracked by using an arrayof wireless access points and certain location tracking algorithms. Thelocation of patients can also be tracked using the same scheme.

Wireless audio systems: In such systems, P-Nodes 104 a-104 n can resideon devices such as wireless microphones and wireless musicalinstruments, e.g., electric guitar, and wirelessly transmit audio orvoice signals. The A-Node 102 can reside on devices such as wirelessspeakers, amplifiers, cellular phones or access points enablingsubsequent data transmission. The devices having A-Node 102 willwirelessly receive data from the devices having P-Nodes 104 a-104 n.

Wireless video systems: In such systems, P-Nodes 104 a-104 n can resideon devices such as wireless cameras (or any device containing a camerasuch as a laptop, cell phone, etc), digital video disk (DVD) players,television tuners and television set top boxes. Such devices cantransmit video signals. The A-Node 102 can reside on devices such aswireless displays, access points, or access points enabling subsequenttransmission. The devices having A-Node 102 will wirelessly receive datafrom the devices having P-Nodes 104 a-104 n.

The above systems typically communicate wirelessly within a range ofabout 25-50 meters in an indoor or outdoor environment, the range of atypical wireless local area network (WLAN). Some applications candictate a larger range.

II. Optimized Asymmetric Wireless System

The commercial viability of asymmetric wireless systems discussed above(shown in FIG. 2) imposes special design constraints. These systems needto continuously transmit sensitive data in real time within a definedrange, typically 25 to 50 meters. Within this range, wirelesscommunication should be highly reliable without any data loss. Manyradios are severely hampered by interference and multi-path fading. Thepresent invention discloses schemes devised to overcome such issues. Inaddition, it can be desirable for P-Nodes 104 a-104 n to use low poweras they may have to operate from small power sources for many days.Furthermore, in many of the applications discussed above, P-Nodes 104a-104 n can be cost sensitive. For example, P-Nodes 104 a-104 n can bepart of disposable wireless patches in the case of healthcareapplications. Also, it can be desirable for P-Nodes 104 a-104 n to bephysically small, typically realized in one, or a few, semiconductorchips so as to have a small footprint. The present invention discloses aradio scheme suitable for such semiconductor chip integration.

In summary, these asymmetric wireless systems can be optimized toachieve at least the following factors:

-   -   High reliability—Highly robust wireless links within its range,        with a very high degree of mitigation capability against the        effects of multipath fading, noise and interference;    -   Low power—Low power dissipation by the P-Nodes 104 a-n in order        to work for several days in continuous transmission mode from a        small power source;    -   Low cost—Low cost P-Nodes 104 a-104 n for commercial viability;        and    -   Small physical size—Suitable radio functionality for        implementation as low cost semiconductor devices (small silicon        area).

The P-Nodes can be constrained low power, low cost, and small. On theother hand, the A-Nodes can sometimes afford to be higher power, highercost and larger due to the asymmetrical nature of various applications.

An asymmetric wireless system that is optimized to achieve the abovementioned factors is referred to as optimized asymmetric wireless (OAW)system. The realization of OAW system requires a highly optimized radioscheme as a foundational technology. This radio can be combined withother functions and technologies to realize an integrated chip(s) basedsolution to implement the P-Nodes and A-Nodes.

Traditionally, as shown in FIG. 2, wireless systems are built using onebasic type of radio (shown as Radio 16 a, 16 b) that establishes awireless link between the two given nodes. This radio typically operateswithin certain defined bandwidth and the overall design is typicallyoptimized for a class of applications. Below are some examples of theradios that have been previously used for local area type of networks.

Wi-Fi: This radio type, which operates in the 2.4 GHz unlicensedIndustrial, Scientific and Medical (ISM) band, has been optimized forwirelessly networking computers and computer related devices within arange up to about 50 meters. The power dissipation and reliability ismodest. The modest reliability can be tolerated by the targetapplications.

Bluetooth: This radio type, which also operates in 2.4 GHz unlicensedISM band, has been optimized to wirelessly cable various peripheraldevices to cellular phones and laptop computers. It is somewhat lowerdata rate, lower power and lower cost than Wi-Fi radios but is shorterrange (about 10 meters) and lacks extensive networking capability. Itsreliability is modest per target applications.

ZigBee: ZigBee is the name of a specification for a suite of high levelcommunication protocols using small, low-power digital radios based onthe IEEE 802.15.4-2006 standard for wireless personal area networks(WPANs). ZigBee is targeted at radio-frequency (RF) applications thatrequire a low data rate, long battery life, and secure networking. Thisradio type operates in the 2.4 GHz, 915 MHz and 868 MHz unlicensed ISMbands. It was defined to wirelessly network various low data ratesensors with data collection devices. It was intended to be lower powerthan Wi-Fi style radios but is little different in practice.

900 MHz Industrial, Scientific and Medical (ISM) Band Radios: Radioshave been realized in this unlicensed band for various consumer andother applications, e.g., cordless phones, remote control toys. Thegeneral characteristics of such radios (power, reliability, cost, etc.)are similar to Wi-Fi radios.

Medical Implantable Communications System (MICS): These radios operatein unlicensed 400 MHz band that has been designated for wirelessimplanted medical devices. It operates in extremely small bandwidth,typically having a short range of about 5 meters and very low data ratesassociated with implanted medical devices.

Wireless Medical Telemetry Service (WMTS): The WMTS radios operate inthe 600 MHz and 1400 MHz. These radios are designed for use in hospitalenvironments. Again, general characteristics of these radios are similarto Wi-Fi radios.

The radios discussed above fall generally in a class defined asNarrowband (NB) radios. There is another class of radios calledultra-wideband (UWB) radios. UWB radios transmit over a much largerbandwidth than NB radios but UWB transmitted power density is far lowerthan the NB radios. For example, the Federal Communications Commission(FCC) defines UWB as fractional bandwidth measured at −10 decibel (dB)points where (f_high−f_low)/f_center>20% or total bandwidth>500 MHz. NBradio, as used herein, is any radio that is not ultra-wideband (UWB)radio. Alternatively, a NB radio may be characterized in terms of theUWB radio, the NB radio having a channel bandwidth that is smaller thanthe UWB radio channel bandwidth by an order of magnitude or more. TheUWB and NB radios have complementary properties as discuss later.

Typically only one radio is used for a given communication link. Thiscould be a single radio type from the above mentioned types or someother custom design. A system and method in accordance with the presentinvention relates to combining multiple radio types with complementarycharacteristics to enable and maintain communication link between twonodes. The complementary radios are switched in and out, as needed, todynamically manage the link characteristics to achieve the desiredoptimization.

When multiple radios have been integrated on a single chip, the purposehas been primarily the optimization of the cost and physical footprintand only one radio is used for a given communication link. One exampleis integration of a wireless protocol utilizing short-rangecommunications technology facilitating data transmission over shortdistances from fixed and mobile devices, creating wireless personal areanetworks (PANs) such as Bluetooth™, and a wireless technology used innetworks, mobile phones, and other electronic devices that require someform of wireless networking capability, such as Wi-Fi, which typicallycovers the various IEEE 802.11 technologies including 802.11a, 802.11b,802.11g, and 802.11n. This integration of multiple radios, e.g.,Bluetooth and Wi-Fi, can be achieved in a single chip or a singlemodule. If such module is deployed, for example, in a laptop computer,the Wi-Fi radio is used to wirelessly network with other computers,whereas the Bluetooth radio is used to connect wirelessly withperipherals such as keyboard and mouse. Another example consists of dualradios used in a mobile phone to support different air interfacestandards, in order to provide compatibility with different wirelessservice providers. For example, a dual-radio phone may support cellularservice such as a global system for mobile communications (GSM) and awireless LAN service such as IEEE 802.11b, and switch between the tworadios depending on which service is available in a geographic area.

In these examples, the communication device selects and uses a singleradio for the duration of the connection or service. These systemscontain no concept of combining multiple radios with complementaryproperties to establish and maintain a single communication link betweentwo or more points. In contrast, the present invention provides a systeminvolving multiple radios with complementary characteristics forselecting amongst and choosing between those multiple radios in order toachieve, for example, one or more of the following performanceobjectives:

-   -   Maximize communications reliability and robustness against        interference and other impairments;    -   Minimize interference to co-existing users;    -   Minimize power consumption; and    -   Accommodate disparity between the uplink and downlink        bandwidths.

Moreover, switching from one radio to another can occur—possiblymultiple times—while a connection or session is in progress. This radioswitching differs from typical channel assignment. Channel assignment isthe process of selecting one out of multiple channels for communication,where the channels share a common structure. For example, in frequencydivision multiple access, all channels are frequency bands; and in timedivision multiple access, channels consist of timeslots. By contrast, inthe present invention, radio switching needs to take into account thestructures of the radios, which are considerably more complex than thestructure of a radio channel. Moreover, the structure of one radio mayhave little in common with the structure of another. For example, thereceiver sensitivity, spectrum usage, permissible radiated power andinherent interference mitigation generally differ between the radios.The differences in radio structures, together with the set ofperformance objectives and the radio propagation environment, can beused to determine the initial radio selection and subsequent radioswitching.

III. Complementary Multi-Radios

In one embodiment, a system 200 in accordance with the present inventiondeploys multiple radios to realize an optimized asymmetric wireless(OAW) system, as shown in FIG. 3. As shown, the P-Nodes 204 a-204 ncomprise multiple radios 216 a 1-216 an. There are correspondingmultiple radios 216 b 1-216 bn on the A-Node 202 to facilitate wirelesscommunication between the P-Nodes and the A-Node. Each of these radios216 a 1-216 an (and corresponding radios 216 b 1-216 bn) can beoptimized for different factors, thereby complementing each other. Atany given time, one or more of these radios 216 a 1-216 an (andcorresponding radios 216 b 1-216 bn) can be activated for communicationdepending on the optimization required and real-time dynamics of thewireless link/channel.

In some embodiments, one of the radios, for example radio 216 a ₁ and216 b ₁, can be the dominant radio that is used most commonly. Thisradio pair 216 a ₁/216 b ₁ can be designed to achieve the optimizationmost critical for the given application. In an OAW system, one can,e.g., achieve low power with high reliability within a given range, forexample, 25 meters. In one example, the P-Nodes 204 a-204 n remainwithin 10 meters of the A-Node 202 most of the time, e.g., more than 50%of the time, more than 60% of the time, more than 70% of the time, morethan 80% of the time, or more than 90% of the time. For thisapplication, the dominant radio (radio 216 a ₁) can be a radio thatoperates at ultra low power within 10 meters of the range. Furthermore,this radio 216 a ₁/216 b ₁ can be designed to be highly reliable withinthis range causing minimum outages in the target operating environment.In this application, another radio, for example the radio pair 216 a₂/216 b ₂, can be employed with a range up to 25 meters but dissipatingmore power than radio 216 a 1/216 b 1. In some embodiments, the outagecharacteristics of radio 216 a ₂/216 b ₂ can be complementary to radio216 a ₁/216 b ₁ so that radio 216 a ₂/216 b ₂ will most likely work ifthere is an outage of radio 216 a ₁/216 b ₁ due to interference,multi-path fading or any other reason. Radio 216 a ₂/216 b ₂ can alsotakeover when P-Node 204 a-204 n moves beyond the range served by radio216 a ₁/216 b ₁. Also, radio 216 a ₂/216 b ₂ can takeover if there is anoutage of radio 216 a ₁/216 b ₁ (provided radio 216 a ₂/216 b ₂ is notimpacted by the circumstances that caused outage on radio 216 a ₁/216 b₁). In some embodiments, a third or more radios 216 a ₁-216 a _(n) canbe used to cover different operating conditions if necessary. In otherembodiments, two radios serve the targeted applications. In theseembodiments, low power can be achieved where low power radio 216 a ₁/216b ₁ is predominantly in use. Other radios can be used only as needed andfor short durations when possible. In aggregate, these embodiments canachieve low power for the P-Nodes, high reliability with minimaloutages, and work within a given range of 25 meters.

The above embodiments illustrate the complementary radios 216 a ₁-216 a_(n) (and corresponding set 216 b ₁-216 b _(n)) and combinations thereofto serve a given requirement. The radios 216 a ₁-216 a _(n) can becomplementary in other ways. Some example complementary propertiesfollow.

Bandwidth: One radio can use a wide bandwidth signal but a narrow timesignal. The other radio can use a narrow bandwidth having a wide timesignal (many cycles of a carrier) and occupy a narrow range offrequencies. Both radios will have different resulting characteristics.

Power Levels: One radio may transmit more power in one band to attainlarger range but the implementation of a transmitter in this band may beless power efficient. The other radio can work in a different band wheretransmission is more power efficient.

Receiver Sensitivity (range/reliability): One radio may be moresensitive in one band but may not be power efficient. The other radio ina different band may be power efficient but less sensitive.

Interference to other radios (“quietness”): One radio can act as aninterferer to other radios in a given radio environment whereas theother radio can be quiet.

Fading Characteristics: Fading of the transmitted signal can result frommulti path effects resulting in signal loss or total outage at thereceiver. Different frequencies suffer different fading. Two radios canbe designed to have somewhat complementary fading characteristics toreduce the probability of both having severe fading under the sameconditions.

The complementary radios can be all narrowband (NB) radios withdifferent optimizations or they all can be Ultra-wide band (UWB) radioswith different optimizations, or they can be a mixture of NB and UWBradios. The UWB and NB radios are highly complementary in many ways asdiscussed below:

-   -   UWB radios typically have a short range in an indoor environment        (up to about 10 meters). On the other hand, NB radios can        provide larger range by transmitting higher power as allowed by        FCC in the operating band.    -   UWB transmitters are typically simple to implement, resulting in        small silicon area and low power dissipation. NB radio        transmitters take up larger silicon area and result in higher        power dissipation than UWB transmitters.    -   UWB receivers are complex and dissipate high power. NB radio        receivers have modest complexity and dissipate modest power.    -   UWB radios cause minimum interference to other radios because        they operate close to the noise floor of other radios. NB radios        cause interference to other radios when operating in unlicensed        bands.    -   UWB can handle some narrowband interference via its de-spreading        (narrowband interference) capability at the receiver. However, a        strong narrowband interferer could degrade its signal quality. A        NB radio can switch to a different channel within its band of        operation when another strong NB interferer appears in the        current channel. It can survive low broadband interference, but        it cannot mitigate strong broadband interference as all NB        channels degrade equally.

Within a given system, the designs with optimum complementary propertiescan be used to realize the radios 216 a ₁-216 a _(n)/216 b ₁-216 b _(n)shown in FIG. 3.

IV. Cost and Physical Size

Embodiments of the present invention disclosed above illustrate how lowpower and high reliability can be achieved for a given range in amulti-radio optimized asymmetric wireless (OAW) system. As statedbefore, OAW systems also need to optimize the cost and physicalfootprint, particularly for the P-Nodes 204 a-n. This can be achievedusing various concepts as discussed below.

Firstly, complementary multiple radio schemes can be chosen in such away that semiconductor implementation complexity of the P-Nodes 204 a-nremains much lower than the complexity of A-Node 202. As discussedpreviously, in a typical OAW system, the data mostly flows from theP-Nodes 204 a-n to A-Node 202. Radios for the P-Nodes 204 a-npredominantly need a reliable transmitter for continuous transmissionand a receiver only for less frequent reception. Radios for the P-Nodes204 a-n can be chosen that are optimized to achieve these two functionsat a low complexity.

As shown in FIG. 3, the multi-radio system also includes a controller240 to coordinate the selection and functionality all the radios. Thecontroller 240 continuously assesses the communication link quality andruns algorithms to determine which radio to use at a given time. It alsosends commands to radios of the A-Node 202 and P-Nodes 204 a-n toactivate/deactivate the radios in real time. Such switching constantlymay maintain the communication link without any data loss. As shown inFIG. 3, the controller 240 can reside in A-Node 202 to keep thecomplexity of P-Nodes 204 a-n low.

Furthermore, in some embodiments, one or more radios out of 216 b ₁-216b _(n) on the A-Nodes 202 can use multiple smart antenna schemes toincrease the link reliability and range. This involves replicating oneor more antennas 220 b ₁-220 b _(n) for the radio or radios chosen forthe multiple-antenna scheme. Multiple antennas add complexity to thechosen radio or radios since multiple radio frequency (RF) transceiversmust be built for the multiple antennas and a signal processor is neededfor antenna combining algorithms. The corresponding radios of P-Nodes204 a-n can still have single antenna schemes 216 a ₁-216 a _(n). Thisembodiment provides the advantages of multiple antennas to increase therange and reliability of the wireless link, but only adds the circuitand processing complexity to the A-Node 202 to reduce the complexity andcost of the P-Nodes 204 a-n.

The above mentioned embodiments help to keep the P-Nodes 204 a-nrelatively simple and low cost by pushing the complexity to the A-Nodes202.

The deployment of multiple radios, in general, can escalate the cost ifprecautions are not taken. To minimize costs, the multiple radios can beimplemented effectively by sharing resources between them when possible.The different elements of a typical radio, shown as 216 in FIG. 4, canbe described as below.

MAC (Media Access Control) 306: The MAC section implements a protocolthat allows data to flow through the radio to and from multiple sources.

Baseband Processor 304: The baseband section modulates or demodulatesthe data and performs other signal processing functions for the radio tofunction and contains digital/analog and analog/digital converters tointerface to the radio frequency (RF) transceiver.

Radio Frequency (RF) transceiver 302: The RF section converts thebaseband analog signal to radio frequency that is fed to antenna 220 fortransmission. Signal received from antenna 220 can be converted back tothe baseband signal.

Antenna 220.

To reduce costs, it is desirable to use complementary radios whereresources of the above mentioned sections are shared or configured torealize multiple radios, thereby reducing overall semiconductorimplementation costs. For example:

-   -   RF: The RF transceiver 302 can be reconfigurable to realize        different types of radios by varying carrier frequencies,        bandwidth, transmitted power, etc.    -   Baseband: The baseband processor 304 can use a programmable        processor to implement certain functions for different radios.        Certain sections of the baseband can be hardwired for different        radios. Other sections of the baseband can be shared and reused        for different radios. Such mixed programmable/custom        architecture typically results in a low cost implementation.    -   MAC: A single MAC 306 protocol can be designed to serve multiple        chosen radios. Furthermore, the main core of the protocol can be        implemented using a programmable processor that provides some        customization for different radios.    -   Antenna: Antenna 220 architectures can be defined to work at        wide ranging carrier frequencies and bandwidths to support        multiple radios.

The combination of various concepts discussed in this section can resultin cost effective and physically small chipsets for the P-Nodes 204 a-nand A-Node 202. Certain specific embodiments of these concepts arediscussed below.

V. Complementary NB/UWB System

As disclosed herein, multiple complementary radios in an OAW system cancomprise:

-   -   All NB radios with different desired characteristics;    -   All UWB radios with different desired characteristics; or    -   A mix of NB and UWB radios.

One embodiment of a multi-radio scheme contains one NB radio 452 and oneUWB 450 radio, as shown in FIG. 5. This NB/UWB scheme can be useful fora variety of OAW systems. As discussed before, the NB 452 and UWB 450radios have complementary characteristics, making them suitable for anOAW system. The complementary UWB/NB radio system can operate as shownin FIG. 6. The ranges of the UWB and NB radios are respectively X andX+Y, where the UWB range is usually smaller than the NB radios. In manyembodiments, the P-Nodes remain primarily within distance X of theA-Node, in range of the UWB radio. If P-Nodes move beyond distance Xfrom the A-Node, but remain within the X+Y range, the NB radio can takeover. Also, if the UWB radio suffers an outage for any reason, the NBradio can be used for communication. Dominant use of the UWB radioresults in overall lower power dissipation and causes minimalinterference to other radios. On the other hand, the NB radio, whichprimarily backs up the UWB radio, guarantees a larger system range up toX+Y. The availability of both UWB and NB radios can greatly increase thesystem reliability due to radio diversity. The UWB and NB radiosnormally suffer outages due to different types of circumstances(different interferences, different multi-patch fading effects,different wall penetration properties, etc.). Therefore, this embodimentincreases the probability that one of the radios is available forcommunication.

As mentioned previously, there are many types of standards based radiosthat can be deployed as NB radios, including Wi-Fi, Bluetooth, ZigBee,WMTS, MICS, 900 MHz ISM band radios, 2.4 GHz ISM band radios, 5 GHz ISMband radios, 60 GHz ISM band radios, etc. In some embodiments, custom NBradios can be deployed as dictated by the system requirements.

The multi-radio system embodied in FIG. 7 exemplifies another optimizedsolution for many current and emerging applications. As shown, thesystem employs a UWB transmitter 550 a on the P-Nodes 504 a-n andcorresponding UWB receiver 550 b on the A-Node 502. The UWB transmitter550 a and receiver 550 b can be asymmetrical. Typically, the UWBtransmitter 550 a section can be built in a small silicon area anddissipates low power. The UWB receiver 550 b has a more complex siliconimplementation and dissipates higher power than the correspondingtransmitter 550 a. In target applications, P-Nodes 504 a-n mostlytransmit the data to A-Nodes 502, and therefore mostly use this link.P-Nodes 504 a-n also implement a Wi-Fi compatible radio 560 which is aNB radio. There is corresponding Wi-Fi radio 562 on A-Node 502 forcommunication with P-Nodes 504 a-n. The Wi-Fi radios 560 and 562 can useone or more modes of the Wi-Fi standard—802.11, 802.11b, 802.11g,802.11a, etc. The Wi-Fi radios 560 and 562 can be used for communicationin at least the following circumstances:

-   -   When P-Nodes 504 a-n move out of the range covered by UWB radio        550 a/550 b.    -   If UWB radio 550 a/550 b suffers an outage due to some other        reason.    -   When A-Node 502 transmits data to P-Nodes 504 a-n (assumed to be        infrequent for target applications).    -   On demand wherein an application can force the use of Wi-Fi        radio 560/562.

Unlike the UWB transmitter 550 a and UWB receiver 550 b, the NBtransmitter 560 and receiver 562 can be symmetrical. Their silicon areaand power dissipation are comparable for both transmit and receivefunctions, and both transmit and receive functions take modest amount ofsilicon area and dissipate modest power. The use of Wi-Fi radio 560 and562 as a NB radio results in an additional advantage: by making thesystem compatible with Wi-Fi standard based devices, the P-Nodes 504 a-nand A-Nodes 502 can communicate with other Wi-Fi enabled devices.

The Wi-Fi radio can be further enhanced, if needed, by using multipleantennas 570 a-n on the Wi-Fi radio of the A-Node 502. The correspondingWi-Fi radio of the P-Node 504 a-n can use a single antenna to reducecomplexity. Through multiple antennas processing gain, the Wi-Fi link ismore robust with a larger range. The multiple antenna configuration canthereby increase the system reliability and robustness at no additionalcomplexity to the P-Nodes 504 a-n. Although the complexity, cost andpower of the A-Nodes 502 increase when using multiple antennaprocessing, in many embodiments, this is not a sensitive issue in thetargeted OAW systems.

In embodiments using complementary radios in a communication system, twomethodologies are employed: where only one radio is active at a time,which will be referred to hereinafter as the “Unicast” methodology; andwhere two or more complementary radios are active at the same time,referred to hereinafter as the “Simulcast” methodology. The followingdescribes the feature of these methodologies in more detail.

(a) Unicast Methodology

The unicast methodology includes initial radio selection, whereby aradio is chosen from multiple radios to initiate a new connectionbetween two devices, and radio switching, whereby one radio is switchedto another during the course of a connection. It is also feasible forthe unicast methodology to consist solely of initial radio selection orsolely of radio switching. When the unicast methodology consists solelyof radio switching, the initial radio to be used for a new connectioncan be chosen by any of a number of means, e.g., random selection, useror factory configuration, or in accordance with a default setting, orothers. The following sections describe initial radio selection andradio switching in more detail.

(i) Initial Radio Selection

The method for initially selecting a radio for a new connection dependson the performance objective. The performance objective may be hardwiredor user-programmable. Example performance objectives are described inthe following sections.

(1) Minimal Power Consumption

In one embodiment, the objective is to minimize power consumption, andthe initial choice of radio depends on the different radio structures.For example, a multi-radio device may include a narrowband (NB) radioand an ultra-wideband (UWB) radio as described herein. The RF andbaseband circuitry implementing the UWB radio may operate with lowertransmission power than the narrowband radio. Accordingly, one wouldchoose UWB, the radio with lower transmit power, for initiating theconnection.

(2) Minimal Interference to Other Devices

In another embodiment, the objective may be to minimize the interferencecaused by the new connection to other devices sharing the radiospectrum. In one embodiment, the initial choice of radio is based on thedifferences in radio structures. Consider a multi-radio devicecomprising a NB radio and a UWB radio. If NB radio devices sharing acommon air interface standard are the sole users of the radio spectrum(as a result of government regulation, for example), and the airinterface provides for cooperative channel partitioning, then the NBradio is preferred for initiating a new connection.

In some embodiments, however, the devices sharing the radio spectrum maynot be cooperative or even known a priori. In this situation, a UWBradio offers the advantage of having a very low radiated power spectraldensity—potentially below the thermal noise floor—and hence would be thepreferred initial radio.

In an alternate embodiment, measurements of the radio environmentexperienced by each radio can be used to predict the amount ofinterference introduced. Consider a system consisting of a mobile deviceand a base station, wherein the base station to mobile connectioncomprises the downlink connection and the mobile to base stationconnection comprises the uplink connection. At the base station, onemeasures the power spectral density (PSD) over the spectrum rangecorresponding to each radio. The received power for a radio then servesas a predictor of the interference from the new downlink connection onexisting users for that radio. The lower the received power for a radio,the less interference the corresponding downlink is likely to produce.

Similarly, at the mobile device, the power spectral density is measuredover the spectrum range corresponding to each radio. The received powerfor each radio at the mobile device is a predictor of the interferencefrom the new uplink connection on existing users for that radio.

As an alternative to measuring the power spectral density over thespectrum range, the received background noise and interference powerlevel can be measured individually on each channel of the radiospectrum. This can be done at either of the two communicating devices.To perform the tests on the different radios and different radiochannels, quiet periods or quiet intervals—intervals during which allthe devices do not transmit—can be used. For example, such quiet periodsare described as part of the 802.11 protocol specification.

In some embodiments, the initial radio is selected to minimize downlinkinterference or uplink interference. In other embodiments, the radio isselected to minimize an aggregate of both uplink and downlinkinterferences. For this approach, the power received on the uplink anddownlink for each radio are aggregated, and the radio with the lowestaggregate received power is selected. For example, the mobile device maycommunicate the downlink interference estimates to the base station overa control channel; the base station can aggregate the uplink anddownlink interference for each radio and select an appropriate radio.

In another embodiment, the communications system is capable of using oneradio for the downlink communication and optionally a different radiofor the uplink communication. In this system, the system need notaggregate the uplink and downlink interference estimates to performradio selection. Instead, the downlink radio can be chosen to minimizethe downlink interference, and the uplink radio can be chosen tominimize the uplink interference.

(3) Maximal Reliability of New Connection

In some embodiments, the most important objective is not to minimizeinterference to other devices, but rather to maximize the reliability ofthe new connection. To accomplish this, the signal quality of thecommunications for each candidate radio can be estimated or predicted.In one embodiment, the communications protocol allows for each radio totransmit a pilot signal on the downlink, the uplink, or optionally bothlinks. The pilot signal may include, e.g., a sequence of symbols or databits. Alternatively, the signal quality can be measured directly fromthe symbols or data bits of the control signals or data signals that areordinarily transmitted during the course of communication. This latterapproach has the advantages of not using the additional radio bandwidthrequired by the pilot signal approach for signal quality estimation, andis more amenable to backward compatibility with existing radiostandards. On the uplink, the base station receiver measures the signalquality for each radio using a signal quality estimator, which will bedescribed shortly. Likewise, the mobile receiver measures the signalquality of each radio on the downlink. The radio is chosen with the bestuplink signal quality or the best downlink signal quality.

In some embodiments, the radio may be chosen based on both uplink anddownlink signal quality predictors. The appropriate radio can be chosenby aggregating the signal quality statistics together at thecommunications device that performs the radio selection. There areseveral ways of accomplishing this aggregation of signal qualitycharacteristics. For example, the mobile device can communicate thedownlink signal quality estimates to the base station over a controlchannel. The base station can then compute a score for each radio as thelesser of its uplink quality and its downlink quality, and can selectthe radio with the highest score. Alternatively, the base station maynarrow the field to only those radios whose uplink and downlink signalquality exceed a minimum threshold. From this group, the base stationthen selects the radio that maximizes downlink signal quality or uplinkquality.

In a further embodiment, the communications system uses one radio forthe downlink communication and optionally a different radio for theuplink communication. In this system, there is no need to aggregate theuplink and downlink signal quality predictors to perform radioselection. Instead, the system can choose the downlink radio with themaximum downlink signal quality predictor, and chooses the uplink radiowith the maximum uplink signal quality predictor.

(4) Support Uplink and Downlink Bandwidth Disparities

In some embodiments, there may be a large disparity in the downlink anduplink data rates. For example, in a mobile Web access application, themobile device spends a large fraction of time downloading Web contentafter clicking on http hyperlinks. Such usage patterns results in largeamounts of data being sent on the downlink but little data transmittedon the uplink. We accommodate this disparity in uplink and downlinkbandwidths with a communications system capable of using one radio forthe downlink communication and optionally a different radio for theuplink communication; for example, selecting the UWB radio for thedownlink and the NB radio for the uplink.

(ii) Signal Quality Estimation

As described above, several of the methods require an estimate of thesignal quality. There are many possible methods of estimating signalquality. In one embodiment, the signal quality can be estimated as thereceived signal strength indicator (RSSI). In another embodiment, thesignal quality can be estimated as the packet error rate or bit errorrate. In another embodiment, the signal quality can be estimated bymonitoring the background noise and interference level of the link; thehigher the background noise and interference level, the lower thequality of the link. Another embodiment for estimating the signalquality is:Estimated signal quality=∥s∥ ² /∥s−∥s∥ ² /∥d ² *d∥ ²,where s is the received signal vector immediately prior to decisionslicing, d is a known pilot vector of symbols, and ∥.∥ denotes the normof a vector. The received signal vector and the pilot vector have thesame prescribed number of symbols. Typically, 20 or more symbols aresufficient, and more symbol generate a more accurate signal qualityestimate. Alternatively, in the absence of known pilot symbols, as wouldbe the case if signal quality estimation is performed directly on thedata or control signal, a decision-directed approach can be used toderive d. In this case, d is the vector of detected symbols afterdecision slicing.

(iii) Multiple Performance Objectives

The preceding embodiments described procedures that allow a multi-radiocommunications system to meet individual performance objectives. Inother embodiments, a multi-radio communications system can allow forsimultaneously achieving multiple performance objectives using aconstrained optimization approach.

It may not be possible to select a radio that is optimal for everyobjective. For example, a radio that is optimal for communicationsreliability may have suboptimal power consumption. In some embodiments,such a system considers one objective from various objectives to havethe greatest importance; hereinafter referred to as the primaryobjective. For each of the remaining objectives, a threshold ofacceptable performance is set; hereinafter referred to as theperformance constraint. The constrained optimization approach can bedescribed by the following: find the radio that optimizes the primaryobjective, subject to the performance constraint being met for the otherobjectives.

FIG. 8 shows a flow chart for addressing the constrained optimizationapproach. Referring to the FIG. 8, for each non-primary objective,determine the subset of radios satisfying the performance constraint,via step 802. Depending on the non-primary objective, methods forexecuting step 802 are described above for the Unicast Method tominimize power consumption, minimize interference to other devices,maximize reliability of new connection, or support uplink and downlinkbandwidth disparities.

Next, take the intersection of all subsets derived from the previousstep to determine the candidate set of radios, via step 804. Finally,from the candidate set of radios, choose the radio that optimizes theprimary objective, via step 806. Methods for executing step 806 giventhe primary objecting are also described herein.

In an example embodiment, suppose the primary objective is to minimizeinterference, subject to achieving a minimum signal quality, in adual-radio system comprising a narrowband (NB) radio and anultra-wideband (UWB) radio. First, procedures described herein can beapplied to estimate the signal quality for both the narrowband and UWBradios, and determine a candidate set of radios with acceptable signalquality. If both radios meet the performance constraint, then aprocedure can be used to pick the radio that minimizes interference. Ifonly one radio meets the performance constraint, that radio can bechosen. If neither radio meets the constraints, the constraints can berelaxed to find a feasible solution.

(b) Simulcast Method

In the simulcast method, both radios are active at the same time. Bothradios simultaneously transmit, and the receiver combines the signalsfrom both radios. Several uses are envisioned for this method. Forexample, when switching from one radio to another, the simulcast methodcan help ensure that the connection remains throughout the switch sothat there is no outage; i.e., it provides soft handoff ormake-before-break switching between the two complementary radios.Alternately, when reliable communications are of paramount importance,both radios can transmit simultaneously all the time. The simulcastmethod is effectively an advanced form of radio diversity, which can beexploited by the receiver.

In one embodiment, two complementary radios use the same symbolconstellation alphabet for encoding data, e.g., Binary Phase-ShiftKeying (BPSK), and the signals from the two radios can be combined inbaseband. There are many ways to perform the combining. In oneembodiment, the signal from each radio undergoes its normal receiveprocessing (down conversion from RF to baseband, amplification, samplingand equalization/matched filtering), except that in the final stagebefore slicing, the baseband signal of each radio path immediately priorto slicing are summed together, and the combined signal goes to a singleslicer. In an alternate embodiment, an enhanced form of RAKE receptionis used:Input to slicer=c1,1*x1[1]+ . . . +c1,n*x1[n]+c2,1* x2[1]+ . . . +c2,m*x2[m]

ci,j=the j-th tap, or coefficient, of the RAKE filter for radio i

xi[j]=the j-th time sample of baseband signal of radio i

A RAKE receiver is a radio receiver designed to counter the effects ofmultipath fading by using several sub-receivers called fingers, whereineach finger independently decodes a single multipath component that arelater combined in order to make the most use of the differenttransmission characteristics of each transmission path. The taps of theRAKE filter can be derived for each of the complementary radios usingany of a number of methods known in the art; for example, maximum ratiocombining (MRC) or optimizing for minimum mean square error (MMSE). Thetime between successive taps and between successive baseband signalsamples may be the symbol period, or it may be a fraction of the symbolperiod, in the case of Nyquist sampling or over-sampling.

Combining of the signals from the two radios before slicing can improvethe reliability of the communications, providing robustness againstchannel impairments in one or both of the radio paths.

VI. Robust Radio Switching Protocols

Radio switching is the process of changing from one radio to anotherafter a connection is established in order to improve on one or moreperformance objectives for the connection.

(a) Radio Switching

In one embodiment, the steps for radio switching comprise the following:

Step 1: For each performance objective of interest, set a threshold ofacceptable performance objectives and monitor each performance objectivefor the current radio using methods as described herein. For example, ifthe performance objective is minimizing interference, monitoring ofinterference can be performed. If reliability is the performanceobjective, the signal quality can be estimated for the current radio. Ifboth reliability and interference objectives are of interest, monitorthe predictors for both objectives for the current radio;

Step 2: If there is only one performance objective and its measuredperformance metric falls below the acceptable threshold, switch to analternate radio. If there are multiple performance objectives, switch toan alternate radio based on one of the following criteria: (i) if anyone performance objective is not met; (ii) if all performance objectivesare not met; or (iii) if the primary performance objective is not met.If there are more than one alternate radios to choose from, then theoptimal radio can be selected using any one of the methods outlinedherein; and

Step 3: After switching, optionally return to Step 1.

In an alternate embodiment, the performance objective is continuously orperiodically monitored for some or all of the radios, e.g., monitoringfor the best signal quality, the lowest interference or a combination ofperformance objectives. If the current radio is not the optimal radio,then switch to the optimal radio. If there is only one performanceobjective and if the performance metric of at least one alternate radioexceeds that of the present radio by some prescribed amount, then switchto the best alternate radio. If there are multiple performanceobjectives, switch to an alternate radio if (i) a majority or all of theperformance metrics of at least one alternate radio exceed those of thepresent radio by some prescribed amount; or (ii) the primary performancemetric of at least one alternate radio exceeds that of the present radioby some prescribed amount.

(b) Handshaking Protocols

As stated earlier, a performance objective of the communications systemcan be increased reliability. Hence, when communication using one radioexperiences poor quality, excessive radio interference or otherimpairments, it can be desirable to switch to an alternate radio.However, the control signal messages that direct the overallcommunications may be transmitted on the same poor qualitycommunications channel as the data. A problem is how to signal the radioswitching reliably, since the radio switching is needed precisely whenthe communications channel is experiencing poor quality. If the controlsignaling is not done correctly, the transmitter and the receiver mayend up in a state where they are not in agreement as to which radio touse, resulting in a broken communications link. The present inventiondiscloses a communications protocol method which can ensure highlyreliable switching from one radio to another, even if the communicationschannel over which the control messages are transmitted is unreliable.

In many practical systems, the two wireless devices communicating witheach other differ in the amount of power available to them. For example,in a cellular telephony application, a cellular phone generallycommunicates with a base station. The base station is fixed in locationand connected to the power grid, so it does not have the powerlimitations imposed upon a battery-powered cellular phone. Thisdifference in the amount of available power is not limited to whetherthe device is portable or stationary.

The cellular phone may comprise a SmartPhone. Although there is nostandard definition of a SmartPhone, such a device is generally acellular phone offering advanced capabilities, including but not limitedto Electronic Mail (E-mail) and Internet capabilities. A SmartPhone canbe thought of as a mini-computer offering cellular phone services.SmartPhones commonly use operating systems (OS) including the iPhone OSfrom Apple, Inc., the RIM Blackberry OS, the Palm OS from PalmSource,and the Windows Mobile OS from Microsoft, Inc. Other operating systemscan be used.

For example, in a medical sensor network, a sensor device may be placedon the body to collect physiological data, and then wirelesslycommunicate the data to a SmartPhone. Both devices are portable andrequire self-contained power sources, but the sensor device may have asmaller form factor and be constrained to run on a smaller battery thanthe SmartPhone. The sensor device may be designed to be disposable andsupplied with a cheap, low capacity battery, whereas the SmartPhone is areusable device designed with a more expensive, higher capacity battery.In summary, there may be a disparity in the energy capacities of twodevices communicating over a wireless link because of differences intheir mobility (stationary versus portable), physical size and cost.

Because processing power is proportional to energy usage, it can bedesirable to design the communications protocol for radio switching tohave low compute processing requirements. However, if the switchingprotocol is asymmetric, and designed to support different amounts ofcompute processing at different radio nodes, then radios with lowerpower capacity can conserve energy by doing less processing, whilehigher power capacity radios will do more processing.

The communications protocol method of the present invention isapplicable to point-to-point as well as multiple access systems. Asdescribed herein, the dynamic radio switching can be integrated togetherwith the selection of which radio channel to use. The partitioning ofradio spectrum into channels can be accomplished by frequency bandpartitioning, by time slot partitioning, by the use of frequency hoppingsequences, direct sequence spreading codes, pulse position offsets,pulse position hopping, or by other means.

The following embodiments exemplify approaches to switching between abase node device and a peripheral node. In some embodiments, the basenode consumes more resources than the peripheral node or nodes. Forexample, as illustrated in the following embodiments, the base node cancomprise a high-powered device (HPD) and the peripheral node or nodescan comprise low powered devices (LPD). A specific embodiment comprisesthe cell phone and cell tower arrangement as described above. Those ofordinary skill in the art will appreciate that the following protocolsreadily generalize to alternate embodiments, e.g., where the two devicesin communication are of similar power capacity.

FIGS. 9 and 10 depict one embodiment of the communication protocolmethod for a HPD and a LPD, respectively. The forward link is thecommunication link from the LPD to HPD, and the reverse link is thecommunications link from the HPD to the LPD. The HPD monitors thecommunications quality of the forward link on the Current Channel of theCurrent Radio (step 602), as described above. The HPD determines whetherthe communication quality is acceptable (step 604). If the communicationquality becomes unacceptable, it then selects a best Alternate Channeland a best Alternate Radio (step 606). The HPD then transmits a controlmessage on the reverse link to the LPD, indicating the Alternate Channeland the Alternate Radio to switch to (step 608). The HPD then switchesto the Alternate Channel and Alternate Radio (step 610). It listens onthis new channel and radio for an acknowledgement message from the LPDindicating that it had received the message to switch to the AlternateRadio and Alternate Channel, as well as for any data communication fromthe LPD (step 610). Verification that the message is a validacknowledgement or a valid data packet can be accomplished using by anumber of ways; for example, by use of a cyclic redundancy check or achecksum. By listening for the acknowledgement on the new AlternateChannel of the Alternate Radio (step 612), the communications of theacknowledgement avoids using the already impaired Current Channel of theCurrent Radio. If the HPD does not receive an acknowledgement within aprescribed time interval, it will retransmit the control message toswitch to the Alternate Radio and Alternate Channel (step 614).Optionally (not shown in FIG. 9), the HPD may re-evaluate the candidatechannels of the candidate radios to select a new best Alternate Radioand Alternate Channel. The HPD will then periodically retransmit thecontrol message to switch to the Alternate Radio and Alternate Channeluntil it receives an acknowledgement from the LPD. Once theacknowledgement is received, the switch to the new Alternate Channel ofthe Alternate Radio by the HPD and LPD is complete and the HPD returnsto monitoring the forward link (step 602).

In contrast with the operation of the HPD, the steps in thecommunications protocol taken by the LPD (shown in FIG. 10) arecomputationally relatively simple. If the LPD receives a control signalmessage on the Current Channel of the Current Radio from the HPDindicating that that it should switch (step 702), the LPD will switch tothe specified Alternate Channel of the Alternate Radio (step 704). Itthen sends an acknowledgement to the HPD on the Alternate Channel of theAlternate Radio, indicating that it received the message to switch (step706). It then uses the Alternate Channel of the Alternate Radio forsubsequent data transmission on the forward link.

In a related embodiment, the operation of the communication protocol isdepicted in FIG. 11 for the HPD. The HPD monitors the communicationsquality of the forward link on the Current Channel of the Current Radio(step 602). The HPD determines whether the communication quality isacceptable (step 604). If the communication quality becomesunacceptable, the HPD selects a best Alternate Channel and bestAlternate Radio (step 606), and then transmits the control message“Switch to the Alternate Channel and Alternate Radio on the forwardlink” to the LPD (step 608). As before, it then listens on the AlternateChannel of the Alternate Radio for an acknowledgement from the LPD (step610 a); however, the HPD will concurrently continue to receive data fromthe LPD on the Current Channel of the Current Radio until it receives anacknowledgement from the LPD on the Alternate Channel of the AlternateRadio (step 610 a). This method introduces additional complexity to theHPD, but has the advantage of minimizing potential lapse or dead time indata communications during the radio switch.

In another embodiment, FIGS. 12 and 13 depict the operation of thecommunication protocol method for the HPD and the LPD, respectively. Asbefore, the HPD monitors the communications quality of the forward linkon the Current Channel of the Current Radio (step 602). The HPDdetermines whether the communication quality is acceptable (step 604).If the communication quality becomes unacceptable, the HPD selects abest Alternate Channel and best Alternate Radio (step 606), and thentransmits the control message “Switch to the Alternate Channel andAlternate Radio” to the LPD (step 608). It then switches to theAlternate Channel, Alternate Radio (step 610 b) for the forward link. Itlistens on this new channel and radio for data communication from theLPD, but does not wait for an acknowledgement from the LPD (step 610 b).Instead, the HPD will periodically retransmit the message “Switch toAlternate Radio, Alternate Channel on forward link” to the LPD until itreceives data on the new channel and radio. The switch to the newAlternate Channel of the Alternate Radio by the HPD is complete once theHPD begins receiving data on the new channel and radio (step 612 a). Asshown in FIG. 13, the corresponding operation required by the LPD isvery simple: when it receives a control message instructing it to switch(step 702), the LPD will switch to the specified Alternate Radio,Alternate Channel on the forward link, and perform subsequent datatransmission on the new channel and radio (step 704). This embodimenthas the advantage of a simplified communication protocol for both theHPD and the LPD, and is particularly suitable in applications where datais sent either continuously or at frequent, regular intervals on theforward link.

FIG. 14 depicts the operation of the HPD in a variation of theaforementioned method. As before, the HPD monitors the communicationsquality of the forward link on the Current Channel of the Current Radio(step 602). The HPD determines whether the communication quality isacceptable (step 604). If the communication quality becomesunacceptable, the HPD selects a best Alternate Channel and bestAlternate Radio (step 606), and then transmits the control message“Switch to the Alternate Channel and Alternate Radio” to the LPD (step608). The difference is that the HPD continues to listen on the CurrentRadio, Current Channel for data from LPD on the forward link (step 610c). As long as it continues to receive data on the current radio andchannel (step 612 a), the HPD will periodically retransmit the message“Switch to Alternate Radio, Alternate Channel on forward link” to theLPD (step 614). Once the HPD stops receiving data for a prescribed timeinterval on the current radio and channel, it then switches to theAlternate Radio and Alternate Channel for subsequent reception of datafrom the LPD (step 616). This method of operation is most suitable forapplications where data is sent either continuously or at frequent,regular intervals on the forward link.

The previously described protocols can also be applied in the case wherethe roles of the HPD and the LPD are reversed; that is, the forward linkis the communication link from the HPD to LPD, and the reverse link isthe communications link from the LPD to the HPD. The LPD then monitorsthe communications quality of the forward link and initiates the radioswitching. While this method of operation can be suboptimal in terms ofmatching the low processing complexity portion of the protocol with theLPD, it can still help ensure reliable radio switching if the quality ofthe communication link from the HPD to the LPD becomes poor. In analternate embodiment, the LPD may make a request to the HPD to performthe monitoring and initiate the switching on the behalf of the LPD. Thisapproach can be used when the LPD does not have sufficient computationaland/or energy resources to perform the monitoring and radio switching.

Those of ordinary skill in the art will appreciate that the previouslydescribed protocols readily generalize to the case where the two devicescommunicating are of similar power capacity.

VII. Dual Mode Ultra-Wideband/Narrowband Reconfigurable Transceiver

A dual mode reconfigurable radio architecture can operate as anarrowband transceiver and is reconfigurable to operate as a broadbandlow power ultra-wideband transceiver.

(a) Generic Dual Mode Reconfigurable Receiver

FIG. 15 illustrates a generic narrowband receiver 900 comprising alow-noise amplifier (LNA) 902, a reconfigurable bandpass filter 904(which is often realized as part of the LNA output tank), and a bank 906of devices. In this embodiment, the bank of devices includes a pluralityof mixers 911 a-911 n. Each of the mixers 911 a-911 n are driven withdifferent phases 913 a-913 n of the Local Oscillator (LO) signal 910.The most common approach is to use two quadrature phases of the LO, orfour differential quadrature phases. The output of these mixers is inturn filtered and sampled by analog-to-digital converter (ADC) 908 a-908n (filter not shown).

FIG. 16 illustrates the receiver configured into a wideband receiver bybypassing or reconfiguring the filter 904 to be a low pass filter (onetechnique to convert the RLC load into a shunt-peaked load is describedlater) and converting the mixers 906 into sampling switches 906. InComplementary Metal-Oxide Semiconductor (transistor type) (CMOS)technology this is easily done by re-using the existing devices 911a-911 n (in for example, a Gilbert cell) as switches. The switches 911a-911 n are now driven with a periodic square waveform delayed by timedelays 1011 a-1011 n fractions of the period Ti-Tn in order to capturedifferent instants of the waveform. The ADCs 908 are clocked at a slowerrate, but in parallel ADCs 908 capture a wider bandwidth (bandwidthextension is equal to the number of stages in parallel). Whilesignal-ended switches are shown, one of ordinary skill in the artreadily recognizes that this feature extends to differential switchesand to double-balanced switching architectures.

(b) Generic Dual Mode Reconfigurable Transmitter

FIG. 17 illustrates a generic transmitter 1100 configured as anarrowband transmitter in accordance with the present invention. Thetransmitter 1100 includes a power source 1102 coupled to a switch 1104.The switch 1104 is coupled to an inductor-capacitor (L-C) circuit 1106and to an antenna 1108. The L/C circuit 1106 and the power source 1102are coupled to the ground. When in the narrowband mode, the switch 1104provides a periodic signal to the antenna. Phase or frequency modulationcan be applied to the switch while the output power is controlled by theamplitude of the direct current (DC) power source. As seen in FIG. 18,when the transmitter is in UWB mode a single pulse to switch 1104 isprovided. In so doing, it is seen that a single transmitter can bereadily reconfigured into either a narrowband mode or a UWB mode. FIG.19 illustrates an embodiment of a circuit 1250 which can provide eithermode dependent upon the input signal to the transistor 1252.

(c) Dual Mode Reconfigurable Transceiver

A particular embodiment of dual mode reconfigurable transceiver isdescribed in detail below. FIG. 20 illustrates the reconfigurablereceiver 1300 implemented in CMOS technology. Transistors 1302/1304comprise a complementary input stage low noise amplifier (LNA) 1306 withlow impedance to match to the antenna. Transistor 1310 is a programmablecurrent source which can alter the input match and LNA gain 1306 toadapt to varying conditions. Capacitor 1312 and capacitor 1314 are ACcoupling capacitors, and capacitor 1314 couples the alternating current(AC) signal from transistor 1304 to transistor 1302, forming a currentsummation at the drain of transistor 1302. The load of the LNA 1306 isformed by a large low Q inductor, inductor 1301 and inductor 1303, whichforms a peaking load.

The layout of these inductors 1301 and 1303 is particularly important asshown in FIG. 21. This inductors are a stacked series connectedstructure, with spirals on each layer connected in series with lowermetal layers with the correct orientation to increase the magnetic fluxand hence to realize a large inductor. Referring back to FIG. 20,transistor 1316 is connected as a switch between the second layer andsupply. A control signal on the gate of transistor 1316 can short outthe bottom layer turns of the inductor. In this way, if transistor 1316is off, then the load is large peaking load. The resistance of the loadis made up of the bottom metal layers, which are typically thinner in anIC process. When transistor 1316 is turned on, the AC signal is bypassedto supply through transistor 1316 and the load is a small higher Qinductor, which resonates with the load of the LNA 1306. In this way,the LNA 1306 can be reconfigured from a broadband LNA for UWB to anarrowband LNA.

Referring back to FIG. 20, transistors 1318, 1320, 1322 and 1324comprise the core of the mixer/sampler stage. Each transistor 1318-1324is biased to operate with zero DC current as a passive switching mixer.In narrowband mode 1302, these transistors are driven with a localoscillator (LO) 1304 which drives the top pair of transistors 1318-1320with an in-phase (I) 1308 a differential signal, and the bottom pair oftransistors 1322-1324 with a quadrature phase differential signal (Q)1308. The outputs V_(o1) 1326-V_(o2) 1328 are a differential IF outputsignal for the I 1308 a channel and the outputs V_(o3) 1330-V_(o4) 1332are a differential IF signal for the Q 1308 channel. Since the IF loadis capacitive and low pass, the effective load of the mixer seen by theLNA 1316 is time-varying and can be shown to effectively form a resonanttank which provides additional rejection of out of band interference.

In ultra-wideband mode, each transistor/capacitor combination(transistor 1318 and capacitor 1334, transistor 1320 and capacitor 1336,transistor 1322 and capacitor 1338, and transistor 1324 and capacitor1340) forms a sample-and-hold circuit (for example, transistor 1318 andcapacitor 1334) which samples the RF signal directly on the capacitor(capacitors 1334-1340). Each capacitor (capacitors 1334-1340) is sizedlarge enough so that the sampled kT/C noise meets the systemspecifications. The transistor 1318 is thus biased large enough toprovide the bandwidth requirements of the system. The gate of transistor1318 is driven with a clock signal at sampling instant T1 while theclock of transistor 1320, transistor 1322 and transistor 1324 aresampled at instants T1+Δd, T1+2Δd, T1+3 Δd. In this way the bandwidthrequirement of each sampler is reduced by one quarter and four parallelstreams of data are used to capture the signal. The output of eachsampler is amplified by a switched capacitor circuit and then digitizedby the ADC. Alternatively, this sampler can form the core of aDelta-Sigma to capture the signal in the digital domain.

The operation of the circuit can be enhanced by placing a VGA in thereceiver path. The VGA forms the second stage of amplification followingthe LNA. To accommodate both narrowband and broadband modes, the VGA canoperate up to the highest RF frequency in the UWB mode. To save power innarrowband mode, however, the VGA can be re-wired and connected afterthe mixers where the highest frequency of operation is set by the IF andnot the RF signal. The current of the VGA stage is lowered to lower thebandwidth of the mixer.

The most commonly used UWB transmitter circuit includes a H-bridgestructure where the gate of the transistors are driven with the correctsignals as to produce a sharp pulse across the load of either positiveor negative polarity. FIGS. 22A and 22B show the operation of thereconfigurable transmitter 1500 in more detail. Referring to FIG. 22A,in the first of a bit ‘0’ period, transistors 1502 and 1504 are turnedon and transistors 1506 and 1508 are turned off to drive a currentthrough the antenna load. Referring to FIG. 22B, in the second half ofthe period, the antenna is short circuited to ground via transistors1506 and 1504. This simple H-bridge circuit is compatible with low costtechnologies such as CMOS and the control signals for circuit are easilygenerated with digital logic.

This H-bridge can be reconfigured as a narrowband transmitter by drivingthe structure with the period LO signal which can be frequency modulatedin high efficiency mode or even driven as a linear differentialamplifier for standards that require power amplifier (PA) linearity.Each switching transistor can be biased in class A, A/B, C, D, or E, E/Fmodes of operation to achieve the required linearity/efficiencytrade-off. In class D mode, for instance, the load is alternated inpolarity between the supply and ground, which results in maximumradiated power given by the power supply and the antenna impedance.Power control can be introduced by regulating the supply of the circuitor by employing impedance matching.

VIII. KITS

Further provided herein are kits comprising devices of the presentinvention. In one embodiment, an asymmetric wireless system as describedherein can be sold to end users in the form of a kit. The kits cancomprise multiple items, including but not limited to integrated devicescomprising one or more anchor, or base, node devices and one or moreperipheral node devices. The devices can implement multiple radiocommunications. In some embodiments, a peripheral node device is in theform of a patch. In some embodiments, a kit can provide a systemcomprising multiple peripheral node devices and one or more anchor nodedevices. In some embodiments, the nodular devices use integratedApplication-specific integrated circuit (ASIC) implementations forrobust and cost effective communications. The devices can furthercomprise dual mode reconfigurable transceivers as described herein. Insome embodiments, the kit can include a host device with an integratedwireless base. In another embodiment, the kit provides one or moreperipheral node patch devices. These devices may be disposable. Such akit can be useful when the end user, e.g., a hospital, has alreadypurchased a kit comprising an anchor node and needs to replenish thesupply of disposable patch devices that communicate with the anchor.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A method for forming and maintaining a connectionin a communication system comprising: providing a base node comprising afirst set of radios for transmitting and receiving signals, wherein thefirst set of radios comprises a plurality of radios optimized fordifferent performance objectives; providing a peripheral node comprisinga second set of radios for transmitting and receiving signals, whereinthe second set of radios comprises a plurality of radios optimized fordifferent performance objectives, and wherein the base node and theperipheral node are constructed and arranged to wirelessly connect viaboth the first set and second set of radios; selecting a performanceobjective for the peripheral node, the base node, and/or the wirelessconnection from a plurality of available performance objectives, saidplurality of available performance objectives including at least two of:reduced power consumption, reduced interference to other devices,increased channel capacity to support many parallel connections, orincreased reliability of new connection; activating the wirelessconnection between the base node and the peripheral node by selectingradios from the first set and the second set based on the performanceobjective; and switching to different radios from the first set and/orthe second set to improve aggregate wireless link performance withrespect to the performance objective.
 2. The method of claim 1, whereinsaid switching to different radios occurs when performance degrades dueto changes in wireless channel conditions.
 3. The method of claim 2further comprising determining, using the communication system with aidof a processor, one or more conditions under which the base node and/orperipheral node are operating, and switching or maintaining the radiosbased on said conditions and the performance objective.
 4. The method ofclaim 2 wherein the change in channel conditions includes relation ofthe base node or the peripheral node.
 5. The method of claim 1, whereinonly one of the radios is selected or activated to form a connection andonly one of the inactive radios is switched to or activated to maintaina connection.
 6. The method of claim 1, wherein the communication systemselects the performance objective with aid of a processor.
 7. The methodof claim 1, wherein the communication system selects which of the radiosis used to form or maintain the wireless connection in order to meet theperformance objective; with aid of a processor.
 8. The method of claim1, wherein the first set of radios or the second set of radios includesa ultrawideband radio and a narrowband radio.
 9. The method of claim 1wherein the base node consumes more resources than the peripheral node,or the base node consumes more power than the peripheral node.
 10. Themethod of claim 1 further comprising: establishing a forward radioconnection and a reverse radio connection between the base node and theperipheral node, wherein the forward radio connection transmits datafrom the peripheral node to the base node and the reverse radioconnection transmits data from the base node to the peripheral node; andmonitoring the communication of the forward radio connection on the basenode until the communication quality of the forward radio connectionfalls below a performance objective, then transmitting a control messagefrom the base node to the peripheral node using the reverse radioconnection, wherein the control message comprises a message to switch toan alternate radio connection selected by the base node.
 11. The methodof claim 1, wherein selecting the performance objective includesreceiving the performance objective from a user.
 12. The method of claim1, wherein selecting the performance objective includes (1) selecting aprimary performance objective from the plurality of availableperformance objectives, and (2) selecting at least one secondaryperformance objective from the plurality of available performanceobjectives.
 13. The method of claim 12, further comprising radios fromthe first set and the second set to optimize the primary performanceobjective while maintaining a threshold of acceptability for the atleast one secondary performance objective.
 14. The method of claim 1further comprising selecting a new performance objective for theperipheral node, the base node, and/or the wireless connection from theplurality of available performance objectives.
 15. The method of claim14 further comprising selecting radios from the first set and the secondset based on the new performance objective.
 16. A communication systemcomprising: (a) a base node comprising a first set of radios fortransmitting and receiving signals, wherein the first set of radioscomprises a first plurality of different types of radios optimized fordifferent performance objectives; and (b) at least one peripheral nodecomprising a second set of radios for transmitting and receivingsignals, wherein the second set of radios comprises a second pluralityof said different types of radios optimized for different performanceobjectives, wherein the base node and the at least one peripheral nodeare constructed and arranged to wirelessly communicate via both thefirst and second sets of radios, wherein the system selects a primaryobjective and one or more secondary objectives for the peripheral nodeand/or the base node from multiple available performance objectives,said multiple available performance objectives including at least twoof: reduced power consumption, reduced interference to other devices,increased channel capacity to support many parallel connections, orincreased reliability of new connection, wherein the system isconfigured to select a radio from the first set and a radio from thesecond set are based on the primary objective and the one or moresecondary objectives to activate a wireless connection between the basenode and the peripheral node, and wherein the system is configured toswitch to different radios from the first set and/or the second set toimprove aggregate wireless link performance with respect to the primaryobjective while maintaining a threshold of acceptability for the one ormore secondary objectives.
 17. The communication system of claim 16wherein a forward radio connection and a reverse radio connection areestablished between the base node and the peripheral node, wherein theforward radio connection transmits data from the peripheral node to thebase node and the reverse radio connection transmits data from the basenode to the peripheral node; and wherein the communication of theforward radio connection on the base node is monitored until thecommunication quality of the forward radio connection falls below themultiple performance objectives while optimizing the primary objective,then transmitting a control message from the base node to the peripheralnode using the reverse radio connection, wherein the control messagecomprises a message to switch to an alternate radio connection selectedby the base node.
 18. The communication system of claim 16 wherein thebase node consumes more power than each individual peripheral node. 19.The communication system of claim 16 wherein the communication systemselects which of the radio types is used to form or maintain theconnection in order to meet the primary objective and the one or moresecondary objectives.
 20. The communication system of claim 16, whereinthe first set of radios or the second set of radios includes aultrawideband radio and a narrowband radio.
 21. The communication systemof claim 16 wherein one or more conditions are determined under whichthe base node and/or peripheral node are operating, and the type ofradio selected for the connection is switched or maintained based onsaid conditions and the primary objective and the one or more secondaryobjectives.
 22. The communication system of claim 16 wherein when theultrawideband radio type is initially selected for forming theconnection, a narrowband radio is subsequently selected for maintainingthe connection; and when the narrowband radio type is initially selectedfor forming the connection, an ultrawideband radio type is subsequentlyselected for maintaining the connection.
 23. A communication systemcomprising: (a) a base node comprising a first set of radios fortransmitting and receiving signals, wherein the first set of radioscomprises a first plurality of different types of radios optimized fordifferent performance objectives; and (b) at least one peripheral nodecomprising a second set of radios for transmitting and receivingsignals, wherein the second set of radios comprises a second pluralityof said different types of radios with different ranges, wherein thebase node and the at least one peripheral node are constructed andarranged to wirelessly communicate via both the first and second sets ofradios, wherein a distance from the base node to the peripheral node isdetermined, and wherein a radio of a first type from the first set orfrom the second set is selected and activated to maintain a connectionbased on the distance from the base node to the peripheral node, andwherein an inactive radio of the same type from the second set if theradio from the first set was selected, or from the first set if a radiofrom the second set was selected, is activated to form or maintain theconnection.
 24. The communication system of claim 23 wherein the basenode consumes more power than each individual peripheral node.
 25. Thecommunication system of claim 23 wherein only one type of radio isselected and activated to form and maintain the connection.
 26. Thecommunication system of claim 23 wherein communication system selects aperformance objective from multiple available performance objectives,and the type of radio selected for the connection is switched ormaintained based on the performance objective.
 27. The communicationsystem of claim 23 wherein the first set of radios includes anultrawideband radio type and a narrowband radio type.
 28. Thecommunication system of claim 23 wherein the second set of radiosincludes an ultrawideband radio type and a narrowband radio type. 29.The communication system of claim 23 wherein an ultrawideband radio typeor a narrowband radio type is selected to form or maintain theconnection based on the distance from the base node to the peripheralnode.
 30. The communication system of claim 29 wherein the ultrawidebandradio type is selected if the distance falls within a predeterminedthreshold, and the narrowband radio type is selected if the distanceexceeds the predetermined threshold.
 31. The communication system ofclaim 23 wherein when an ultrawideband radio type is initially selectedfor forming the connection, a narrowband radio type is subsequentlyselected for maintaining the connection.
 32. The communication system ofclaim 23 wherein when a narrowband radio type is initially selected forforming the connection, an ultrawideband radio type is subsequentlyselected for maintaining the connection.
 33. The communication system ofclaim 23 wherein a forward radio connection and a reverse radioconnection between the base node and peripheral node is established,wherein the forward radio connection transmits data from the peripheralnode to the base node and the reverse radio connection transmits datafrom the base node to the peripheral node, wherein the communication ofthe forward radio connection on the base node is monitored until thecommunication quality of the forward radio connection falls below aperformance objective, in which case a control message is transmittedfrom the base node to the peripheral node using the reverse radioconnection, and wherein the control message comprises a message toswitch to an alternate radio type for the connection selected by thebase node.